In the can making art, the can body and the sealable tops therefor are typically made in separate operations. Similarly, in making the sealable tops, there are separate operations for making the top and for making the pull tab. Once the separate operations are completed, the pull tabs are affixed to the tops for subsequent sealing to the can body.
As is well known, it is desirable to coat a metal with a lube prior to die punching or stamping thereof. It is desirable to lubricate the metal because this allows the tools to work more efficiently as well as to preserve the cutting edges thereof for a longer period of time.
In the formation of pull tabs from tab stock, a length of a thin flat material such as aluminum is fed through a lubricating device prior to the formation of the pull tab. In the only type of lubricating device known to the applicants, a lube is dripped onto a pair of felt pads between which the tab stock passes. Preferably, the lube should be evenly applied to the tab stock prior to its formation into pull tabs. In practice, however, uniform application has been difficult to achieve.
Specifically, difficulties have arisen due to accumulation in the felt pads of metal scraps and other contaminants. While removal of such materials prior to pull tab formation is desirable, the accumulation thereof in the felt pads will eventually clog the felt pads and disrupt the lube drip rate. As will be appreciated, avoidance of undesirable accumulation entails the undesirable requirement of shutting down the equipment to remove and clean, or to replace the clogged felt pads.
Uneven lube application can also result from drip rate variations caused by machine vibrations and lube evaporation. In the latter regard, low viscosity lubes which comprise approximately 80% evaporative carrier and 20% actual lubricant have been typically employed to accommodate the wicking requirements of the felt pads. That is, while lubes comprising a greater percentage of lubricant would be preferable from a reduction of evaporation standpoint, wicking within the felt pads requires a more watery consistency as opposed to oily consistency.